In automotive gaskets, e.g., cylinder gaskets, fluoroelastomer coated metals have been used as substitutes for the asbestos. For example, Japanese Unexamined Patent Publication (Kokai) No. 62-248459 discloses a composition containing a fluoroelastomer, a polyol, a quaternary ammonium salt accelerator or a quaternary phosphonium salt accelerator, and an acid acceptor.
However, such a composition has a short shelf life and, accordingly, was not necessarily satisfactory because it must be cured for a prolonged period.
On the other hand, it has been known that carboxylic acid is used to form a salt or chelate with the metal ion, whereby the metal ion is inactivated in order to extend the shelf life.
However, carboxylic acids are usually hydrophilic and, thus, incompatible with the components of elastomer compositions. Also, it is difficult to add the carboxylic acid to an elastomer composition.
Moreover, a relatively low molecular weight amine accelerates the curing rate when added to a fluoroelastomer composition, but at the same time, it markedly shortens the shelf life and, accordingly, it cannot generally be employed.
Thus, it is an object of this invention to provide a coating composition containing fluoroelastomer having a prolonged shelf life and decreased curing time.